A field emission device (FED) is generally considered to be a device in which an electron beam is focused between two electrodes, producing a field emission. Typically, the FED may include an electron-emitting material and a light-emitting material. Application of a voltage across the electrodes can cause an emission of electrons from electron-emitting material, which may be used to excite the light-emitting material, resulting in a field emission. Generally, the efficiency of electron emission may depend on the material utilized as the electron emitter. Some examples of such materials include silicon, molybdenum, and diamond. Such devices have been useful in various display applications.
Recent studies have focused on the use of carbon nanotubes as an electron emitting source in FEDs. Carbon nanotubes generally have a cylindrical shape and may emit electrons from their termini, making the ability to modulate the orientation of carbon nanotubes in a device desirable in some cases. Although methods have been utilized to incorporate carbon nanotubes within FEDs, current technology may have some limitations. For example, one method involves patterning a catalyst material on a surface to catalyze growth of carbon nanotubes directly on the surface. While this may allow for control over the average orientation of the nanotubes on a surface, fabrication may be high in cost. Also, growth of carbon nanotubes over a large surface area can be difficult due to incompatibility between the stability of the substrate material and the conditions required for carbon nanotube growth. Another method may involve mixing carbon nanotubes with an adhesive, binder, resin, or other filler material, followed by screen printing the mixture on a surface. However, using this method, it may be difficult to control the density and orientation of the carbon nanotubes in the resulting structure. Also, the filler material may reduce the lifetime and stability of the carbon nanotubes.
Accordingly, improved methods are required.